Magnetic iron-titanium mixed oxide catalysts were prepared through the co-precipitation assisted by microwave-pyrolysis.The influence of Ti doping on the selective catalytic reduction of NO_x over iron oxide was investigated,and the crystal phases and microscopic pore structure of iron oxides after the doping of titanium were also studied by XRD (X-ray diffraction) and N₂ adsorption-desorption test.The results indicate that a strong crystal phase of α-Fe₂O₃ appears within iron oxides prepared through the co-precipitation assisted by microwave-pyrolysis.The addition of titanium can increase the thermal stability of iron oxide,meanwhile,iron-titanium mixed oxide catalysts show the crystal phase of γ-Fe₂O₃ and α-Fe₂O₃ when the molar ratio of Ti is 0.25.The pore size of iron oxides can be refined,and its Brunauer-Emmett-Teller surface and pore volume are increased after the doping of titanium oxide.Thereby its NH₃-SCR activity is improved,and the optimum molar ratio of titanium oxide is 0.25.Under the condition of 60 000/h gas hourly space velocity,more than 90% of NO_x conversion can be achieved over Fe_0.75Ti_0.25O_z at the temperature of 275~400℃.